Place the beef stew meat, pearl barley, carrots, parsnips, potatoes, onion, and garlic into a large freezer bag.
Add the beef broth, dried thyme, dried rosemary, bay leaves, salt, and black pepper to the bag.
Seal the bag, remove excess air, and freeze flat until solid.
When ready to cook, thaw the bag overnight in the refrigerator.
Pour the contents into a slow cooker.
Cover and cook on low for 8 hours until the beef is tender and the barley is cooked through.
Remove the bay leaves before serving.